DMD 1.038 and 2.022 releases

[Robert Jacques]

On Tue, 16 Dec 2008 12:28:43 -0800, Simen Kjaeraas  
<simen.kjaras at gmail.com> wrote:

> On Tue, 16 Dec 2008 18:58:47 +0100, Robert Jacques <sandford at jhu.edu>  
> wrote:
>
>> On Mon, 15 Dec 2008 17:48:21 -0500, mastrost <titi.mastro at free.fr>  
>> wrote:
>>
>>> In this example, myPureFunction looks like a pure function, does it?
>>
>> No it doesn't
>
> So this does not seem pure to you?
>
>    int myPureFunction(int x) {
>      return x;
>    }

Short answer: That's a function, not a delegate and without a 'pure' tag  
it's unreasonable for the complier to know it's logically pure.

Long answer: Your original arguement was:

> But the fact is that when returning a delegate, its closure freezes  
> forever and so
behaves like a local variable and not like a global variable by respect to  
the
delegate :

Which I read to mean that a returned delegate is inherently pure. On a  
second read, I think you mean that the closure heap variables may be  
treated as immutable once a delegate is returned if the delegate doesn't  
mutate them. While an interesting observation, it too is easily broken:

int delegate() impure;

int delegate() getPureFunction(int x){
     int bar(){
         return x;
     }
     int foo() {
         return x++;
     }
     impure = foo;    // The closure may not be considered immutable since  
'x' escapes
     return &bar;
}